We studied the effects of exogenous spermidine (Spd) on free polyamines content and polyamine biosynthesis gene expression in cucumber (Cucumis sativus L. Cv. Jinchun No. 2) seedlings under salt stress with solution culture. Plant height, stem diameter, and fresh and dry weight were significantly reduced by treatment with 75 mmol/L NaCI, while the inhibition of seedling growth was alleviated by spraying 1 mmol/L Spd. Free polyamine content was significantly increased in leaves when exposed to salt stress, and exogenous Spd application to leaves further promoted free Spd and spermine (Spm), but reduced free putrescine (Put). Expression analysis of polyamine synthase genes showed that salt stress up-regulated adc, ode, samdc and spds gene expression, and exogenous Spd application further up-regulated samdc gene expression and down-regulated adc, ode, spds gene expression. The results revealed that exogenous Spd regulated polyamine metabolism in cucumber seedlings under salt stress, inhibited free Put accumulation by reducing adc, ode gene expression, increased free Spd and Spm accumulation by up-regulated samdc gene expression, and alleviated the inhibition of plant growth under salt stress.%以黄瓜品种‘津春2号’( Cucumis sativus Lcv.Jinchun No.2)为材料,采用营养液栽培,研究了外源亚精胺(Spd)对NaCI胁迫下黄瓜幼苗叶片游离态多胺含量和多胺合成酶基因表达的影响.结果表明,75 mmol/LNaCI胁迫下,幼苗株高、茎粗和干鲜重显著降低,外源喷施1 mmol/L Spd处理可明显缓解盐胁迫时幼苗生长的抑制.盐胁迫下叶片游离态多胺含量显著增加,外源Spd进一步促进了游离态Spd和精胺(Spm)的积累,降低了游离态腐胺(Put的积累.多胺合成酶基因表达分析表明,盐胁迫上调了adc、odc、samdc和spds基因的表达,施用外源Spd后进一步上谰了samdc基因,下调了adc、odc、spds基因的表达.表明外源Spd参与了黄瓜幼苗体内多胺代谢的调节,通过下调盐胁迫下adc、odc基因的表达,抑制游离态Put的积累,上调samdc基因的表达促进游离态Spd和Spm的积累,进而缓解盐胁迫对植物生长的抑制.
展开▼
